The present invention relates to a sinker device of a flat knitting machine for biasing a knitted loop in a direction of its being pushed down to a needle bed gap between needle beds arranged opposite in back and front.
The applicant previously proposed a sinker device disclosed by Japanese Laid-open (Unexamined) Patent Publication No. Hei 9 (1997)-31806. In this sinker device, a pivoting portion of a sinker is pivotally supported in a semicircular pivot slot formed in the needle plate, and the sinker is freely turned forwardly and backwardly about a pivot shaft of the pivoting portion of the sinker in the state in which a stitch holding hook of the sinker is always urged in a direction for a knitted loop to be pushed down by elastically urging means. The sinker is provided with a control butt so that the engagement of the control butt with a cam mounted on the carriage can permit the sinker to be retracted from the needle bed gap against a biasing force of the biasing means for the required retracting motion of the sinker in the process of stitch forming. Further, the sinker is provided, at a lower portion thereof, with a sinker rest plate to be freely advanced and retracted with respect to the needle bed gap so that when the sinker rest plate is advanced, with the carriage cam engaged with the control butt of the sinker rest plate, the front end portion of the plate can press down the sinker to hold it in its rest position where the stitch holding hook does not act to urge the knitted loop downwards when the carriage is passed.
The sinker device thus constructed enables the knitted loop to be held by the stitch holding hook under adequate tension from the elastic biasing means and also enables the stitch holding hook to be held in its rest position where no tension is placed on the knitted loop when the carriage is passed, thus providing an enlarged gap for the needle bed gap between the front and back needle beds. This holding of the stitch holding hook in its rest position can provide the advantage that even when the needle bed is racked in knitting a fabric with a thicker yarn, the stitch holding hook of the sinker can be kept from scratching a fabric held by the needles on the opposite needle bed to damage it.
However, in order for the sinker to operate to provide the required actions mentioned above, this sinker device is required to have a control system for controllably advance and retract the sinker and another control system for controllably advance and retract the sinker rest plate.
Also, in this sinker device, since the pivot shaft of the sinker is fixed at a fixed position of the needle plate, when the stitch is formed, the stitch forming edge of the sinker is always held at a fixed position without any advancing and retracting motion with respect to the advancing and retracting direction of the knitting needle.
It is an objective of the present invention to provide a sinker device that can permit a swinging motion of the sinker that is constructed to hold a knitted loop under adequate tension and the rest retention via a single control system.
It is another objective of the present invention to provide a sinker device that can permit the stitch forming edge of the sinker to be advanced and retracted in the advancing and retracting direction of the knitting needle, so as to reduce the stroke of the knitting needle.
In accordance with one aspect of the invention, there is provided a sinker device of a flat knitting machine comprising at least a pair of front and back needle beds which are opposed to each other across a needle bed gap, either or both of which is/are sidable in a lateral direction thereof; a number of knitting needles which are set in needle grooves arranged in series on the needle beds so as to be freely advanced and retracted; sinkers, each having a stitch forming edge and a stitch holding hook and arranged between adjacent knitting needles so as to be freely swingable; and biasing means for biasing a knitted loop downwards to push it into the needle bed gap by the stitch forming hook, the sinker device further comprising sinker jacks which can be freely advanced and retracted with respect to the needle bed gap and on which the respective sinkers are supported in a freely swingable manner, wherein the sinkers and the sinker jacks each have sliding contact surfaces sidably contactable with each other which are each formed at a front side thereof with respect to a swinging pivot point, so that when the sinker jack is advanced toward the needle bed gap to move relative to the sinker, the sinker can take a swinging attitude controlled by the sliding contact relation between the respective sliding contact surfaces of the sinker and the sinker jack so that the sinker can be controllably swung to at least a knitted loop pushing level, a knitted loop releasing level and a stitch forming level.
The sinker forms therein the swinging pivot point, and the sinker jack has a control butt to engage with a carriage cam so as to control an advancing and retracting motion of the sinker jack.
Also, the sinker is so structured that it can be advanced toward the needle bed gap by the sinker jack, while it is kept at its stitch forming level.
According to this construction, the sinker supported on the sinker jack is so biased by the elastic biasing means that its stitch holding hook can be swung downwards and their respective sliding contact surfaces formed on the sinker and the sinker jack are always urged into contact with each other at a location forward of the swinging pivot point. Also, when the sinker jack is advanced and retracted by the carriage cam to move relative to the sinker, the sinker is controllably swung to at least a knitted loop pushing level, a knitted loop releasing level and a stitch forming level by the sliding contact relation between the mutually sidably contactable sliding contact surfaces.
In accordance with another aspect of the invention, there is provided a sinker device of a flat knitting machine comprising at least a pair of front and back needle beds which are opposed to each other across a needle bed gap, either or both of which is/are sidable in a lateral direction thereof, a number of knitting needles which are set in needle grooves arranged in series on the needle beds so as to be freely advanced and retracted; and freely swingable sinkers, each being arranged between adjacent knitting needles and being biased downwards by biasing means, to push a knitted loop into the needle bed gap by a stitch forming hook of the sinker, the sinker device further comprising sinker jacks which can be freely advanced and retracted with respect to the needle bed gap and over which the respective sinkers are disposed, wherein each sinker includes a longitudinally extending shank, a stitch holding hook with a stitch forming edge provided at a front end portion of the shank, a protuberance protruded downwardly from a part of the shank to abut with a supporting surface of the sinker jack, and a sliding contact surface extending forward of the protuberance and formed by a lower surface of the shank to slidably contact with a first projection of the sinker jack being so formed as to vary in level along a longitudinal direction thereof, and wherein each sinker jack includes a longitudinally extending shank, the first projection formed on an upper surface of the shank of the sinker jack confronting the sinker at a front end portion thereof, a supporting surface for supporting the protuberance of the sinker, and a control butt formed at a tail portion thereof to engage with the carriage cam so as to control an advancing and retracting motion of the sinker jack, whereby the advancing and retracting motion of the sinker jack controlled by the carriage cam can make the first projection of the sinker jack move along the sliding contact surface formed on the sinker so that the sinker can take a predetermined swinging attitude in accordance with the varied level of the sliding contact surface.
According to this construction, the sinker is always biased downwards by the elastic biasing means and the protuberance provided in the shank of the sinker is supported on the sinker jack arranged to be freely advanced and retracted with respect to the needle bed gap in abutment therewith so that a knitted loop held on the knitting needle can be urged into the space under the needle bed gap, with adequate tension placed on the knitted loop by the stitch holding hook. As a result of this, the sliding contact surface formed forward of the protuberance of the sinker and the first projection formed in the sinker jack are always press-contacted with each other. When the butt of the sinker jack is advanced and retracted by the cam mounted on the carriage, the sliding contact surface of the sinker and the first projection of the sinker jack are moved relative to each other while they are sidably contacted with each other. Since the sliding contact surface of the sinker is formed to vary in level along the longitudinal direction of the shank, the sinker can take a required swinging attitude for knitting a fabric (knitted loop pushing level, knitted loop releasing level and knitted loop forming level) in accordance with the varied level.
The biasing means is formed by an elastic leg formed to be branched from the shank of the sinker.
According to this construction, the stitch forming hook can be elastically biased downwards by the sinker itself without any extra elastically biasing means such as a spring, thus reducing a component count of the sinker device and also facilitating maintenance such as a parts replacement.
Also, the sinker jack is provided with a second projection to engage with a rear surface of the protuberance of the sinker so as to advance the sinker so that when the sinker jack is advanced farther than a given stroke, the second projection can urge the sinker toward the needle bed gap.
According to this construction, when the knitting needle is retracted along the stitch cam for forming a stitch, the protuberance of the sinker is pushed out by the projection of the sinker jack to advance the stitch forming edge toward the needle bed gap, thus reducing the stroke of the knitting needle to an extent corresponding to such an advance of the stitch forming edge.
As mentioned above, according to the sinker device of the present invention, since controllably advancing and retracting the control butt provided in the sinker jack can permit the sinker to be held not only in a position to place adequate tension on the knitted loop, but also in a rest position to place no tension on the knitted loop, it is only necessary for the sinker device to provide a single control system therefor.